1. Field of the Invention
The present invention relates to an ultrasonic diagnostic apparatus that has a two-dimensional array and three-dimensionally scans a subject.
2. Description of the Related Art
As shown in FIG. 4, a conventional ultrasonic diagnostic apparatus is provided with: a transmitting array 30A including many transducer elements assigned to several transmitting sub-arrays 311, 312 to 31M; a transmitting beam former 40 including several transmitting beam former channels 411, 412 to 41M; in-group transmitting processors 381, 382 to 38M which are configured and arrayed so as to generate an acoustic beam emitted to a subject portion; a receiving array 30B that includes many transducer elements assigned to several receiving sub-arrays 421, 422 to 42N; several in-group receiving processors 441, 442 to 44N connected to the several receiving sub-arrays 421-N; a receiving beam former 46 that includes charge coupling elements for forming delaying elements which are arrayed so as to receive a transducer signal in response to an echo from the acoustic beam, from the transducer element of the sub-array where each of the in-group receiving processors 441-N is connected, and are arrayed so as to delay the transducer signal received by each of the in-group receiving processors 441-N, and includes an adding element for receiving the delayed transducer signal and adding the delayed transducer signal; several processing channels 481, 482 to 48N where this receiving beam former 46 is connected to the several in-group receiving processors 441-N; and an image generator 58 that includes a beam former delaying mechanism where each of the processing channels 481-N synthesizes the receiving beams from the echo in accordance with the receiving signals received from the in-group receiving processor 441-N and a beam former adding mechanism 50 for receiving the signals from the processing channels 481-N and adding them, and generates the image of the subject portion in accordance with the signal received from the receiving beam former 46 (for example, refer to the following patent document 1).
[Patent Document 1] Japanese Patent Application Publication (2000-33087)
However, in the conventional ultrasonic diagnostic apparatus, if a dynamic focus for dynamically changing a focus distance of reception is tried, a clock frequency of the charge coupling element of the in-group receiving processor must be changed, which results in a problem of noise generation. Also, there is a problem that the numbers of the in-group receiving processors 441-N, the processing channels 481˜N and the signal lines to connect them must be increased in order to exhibit the directivity of the reception in a plurality of directions at the same time.